In most works with explosives, the detonation of charges associated with detonators is triggered according to a very precise time sequence, this being so in order to improve the efficiency of the work of the explosive and to better control the effects thereof. The recent appearance of electronic detonator firing systems has made it possible to obtain much greater precision of this time sequence than the precision of conventional pyrotechnic systems.
When implementing electronic detonator firing systems, a significant job of work consists in preparing the firing plan for the detonators corresponding to this time sequence, and then in programming and testing these detonators “at the front”, that is to say in proximity to the blast holes, and then in firing the detonators from a “firing post”, that is to say at a safety distance from the firing zone.
Publication WO 97/45696 describes steps of programming detonators consisting mainly in using one or more programming consoles or units to associate a delay time, in milliseconds, with each of the detonators. The corresponding association table forms a firing plan which is subsequently transferred to a firing console or unit possessing the capabilities and codes for firing the detonators.
This transfer may be carried out by virtue of infrared technology, the latter requiring precise relative positioning of the two units, thereby rendering it difficult to implement in a works environment or worksite.
Other firing systems propose a transfer of these data between the programming console or consoles and the firing console with the aid of linking cables or else with the aid of wireless technologies of Bluetooth type (commercial name). In the first case, it may happen that the cable fails or is mislaid thereby making it impossible to retrieve the data from the programming consoles.
Finally, the technologies used today, be they wire-based or wireless using infrared or Bluetooth, require an electrical power supply to ensure the transfer of data.
There is therefore a need to secure this transfer of data to the firing console using neither cables nor electrical power supply of the console from which it is desired to retrieve the data.
In practice, an operator traverses up and down the works site so as to connect each of the detonators successively and individually to a firing line. The operator's programming unit also being connected to the firing line, it detects the connection of a new detonator and identifies the latter. The operator then inputs, using an alphanumeric keypad of the programming console, a delay time to be associated with each of the successively identified detonators on the firing line.
For the subsequent description, this operation will be referred to as “programming the detonators”.
As a variant, instead of associating a firing cue of delay time type with each detonator, the operator can specify, on his programming unit, a firing cue of drill-hole identifier type on the site in which the detected detonator is placed, the association with a delay time possibly being carried out subsequently on the firing console for example.
During the operation of programming the detonators, a step of identifying the detonators is carried out. This identification consists, in respect of the programming unit, in retrieving a parameter for identifying the detonator connected by exchanging messages on the firing line, this parameter being for example stored in ROM memory of the electronic detonator. The programming unit then stores, in EEPROM memory, the association carried out between this identification parameter and the corresponding delay time or hole number that was input. The resulting table constitutes the firing plan.
As a variant, the identification can consist, in respect of the programming unit, in dispatching to the detonator an identification parameter which will be stored by the detonator, for example in EEPROM memory, the programming unit then storing the association of this identifier and of the firing cue of delay time or hole number type.
When firing sizable shots, this programming operation can rapidly become laborious having regard mainly to the sizable number of detonators to be connected and programmed. Thus, several hours of programming may sometimes be necessary. In this case, the programming operation may be carried out by several operators, each being equipped with a programming console so as to program, with each console, part of the firing plan. In practice, the firing plan is divided up into several zones, the detonators of each of them being connected to bus lines, these bus lines together constituting a network connected to a main line called the firing line. In this configuration, it is commonplace to use one and the same programming console for the programming of one or more bus lines and not to mix on one and the same bus line detonators programmed by different programming units.
Once the programming of all the detonators has been performed, it is moreover commonplace to undertake tests on site with the aid of the programming console(s). These tests are in particular intended to verify that all the programmed detonators are properly linked to the firing line and that no other “intruder” detonator has been connected without having been previously programmed by a programming console.
When several programming consoles have been used for the programming of a firing, each of them contains the identification parameters for only some of the detonators present on the firing line, corresponding only to the detonators programmed by this console. Each console undertakes functions of counting and then of identifying the connected detonators. However, there is reason not to consider the detonators programmed by the other consoles to be intruders. This necessitates mental intervention by the operators so as in particular to compare the number of detonators connected with the number of detonators programmed, without making it possible to easily detect any intruders.
Excluding the case where a single programming console has been used, no programming console contains all the identifiers of the detonators of the firing plan. It is then impossible to test the whole of the firing plan at once.
There is therefore also a need for means which simplify the test operations to be conducted on the firing lines or sets.
Moreover, it may happen that a programming unit undergoes a failure during these programming operations, for example because of a power supply battery fault or of hardware destruction resulting from a worksite accident. Such a situation compels complete reprogramming of the detonators initially stored in the (partial) firing plan of the failed console. A considerable loss of time can thus be caused. It may also happen that the operator cannot terminate his programming operations since the battery is flat and requires recharging.
There is also a need for more effective programming means, in particular in the case of failure of a programming console.